rattling noise from my 99 tacoma

Hello,

My 99 trd tacoma has begun making a rattling noise. The noise is definetely metallic. It is inconsistent such that I cannot predict when it will occur. It is loud enough that one can hear the rattling when both windows are rolled up inside the cab. The noise goes away when gas is applied and usually occurs when the vehicle has warmed up. I noticed when the rattling is happening when at a stop, I can make it go away when I change gear to N or 2 (auto tranny). This is when I'm at a stop. I thought maybe a heat shield may be loose but could'nt find anything loose. tranny fluid is fine. I brought my truck to a local dealer (terrible customer service..thats what I get for bringing my truck to the dealer)but I could not recreate the rattling noise for their tech to diagnose. Of course they end up telling me that my dash is rattling due to broken clips and this may be what I'm hearing and they have to charge over 250 dollars to replace the clips because they have to remove the dash..I dont recall tacomas having clips to support the dashboard. If anyone knows otherwise please let me know. If anyone has experienced this strange rattling please let me know..The rattling is driving me crazy. Sidenote, the tranny is not slipping, shifts gears with no prob, no impact to driveability has occcured since noise appeared, its just very annoying and loud. Any advice/insight on this is appreciated. I've tried to isolate the noise but its too hot under the truck when its at operating temp (dont want to get burned), but it sounds like the noise is near the rear of the motor when listening in front of engine, and seems to be coming from vicinity of tranny. A friend has suggested I check the precat for looseness or damage....

I think you are on the right track as the noise, being metalic and rpm related, is almost certainly from exhaust components or heat shields. You are going to have to get pretty creative to safely recreate the noise (in drive, at a stop, with the brakes applied) as I know I won't be the one to crawl underneath to take a look! This may sound dumb but you could just dial your idle up 100 rmp or so as it sounds as if the rattle only occurrs at the lowest possible rpm. Just a thought.

You may want to check out an exhaust bracket that lies directly above a crossmember right behind the cat. converter. If this wears or gets loose, a portion of the exhaust can rattle lightly against the cross member giving you the noise at idle speed. Good luck

my 99's exhaust was loose and it was
clanking against a broken hanger

I had rocks in my heat sheild, but the big problemo was a broken spring leaf, uggh

I have the same vehicle, and the same noise. No idea what it actually is, have had 2 shops look and say everything from valves to tranny. Ugh. Let me know if you ever figure it out and I'll do the same. Mines been going on for 6-9 months so I dont know how bad it actually is...

it sounds like it may be the cat itself. remove the four bolts that hold it in place and remove it. look inside to make sure the honey comb looking insides are firmly in place. do not do this when hot. if you do not notice any thing by looking put light pressure on it with something to check for any movement. at this time you can also check the rear cat mount. if you have to replace it summit is about $70 cheaper than any place else i could find.

I have had, and have again a rattle like that too, I found out it was a broken leaf spring, and I just found out yesterday that I have it again... UGH!!!

I finally had mine diagnosed and repaired - it was a cracked clutch plate. Only 1600 bucks and it is now noise free!